ADHD is a commonly diagnosed psychiatric disorder that is well-recognized in childhood, an estimated 30 to 50 per cent of whom continue to have an ADHD diagnosis as adults.

Over the past few decades, greater recognition of adult ADHD has led to an increase in the use of stimulant and non-stimulant ADHD medications in Canadian adults. However little data has been available to steer policies regarding the efficacy and safety of these products in adults.

ADHD is characterized by inattention, hyperactivity and impulsivity, which in adults may manifest itself as edginess, shopping sprees, quitting jobs and risky behaviours. ADHD in adults is associated with various conditions including depression, bipolar disorder, substance abuse, personality disorders, anxiety disorders and learning disabilities. Left untreated, ADHD may also result in higher rates of unemployment, poorer work performance and sick leave.

“In recent years prescribing of these medications has more than doubled in Canadian adults, but we have lacked good data for adult use of these drugs upon which to base health policy decisions,” said the report’s lead researcher, Tara Gomes, a scientist at the Institute for Clinical Evaluative Sciences and a researcher in the Li Ka Shing Institute of St. Michael’s Hospital who is principal investigator of the Ontario Drug Policy Research Network.

“We undertook this review to investigate the risks and benefits of these drugs in this understudied and growing adult population.”

The researchers looked at two types of medications used to treat ADHD in adults: stimulants and non-stimulants. They found that adult patients and their physicians reported good responses to these drugs overall. However, some ADHD drugs can be more difficult for adults to access through public drug plans in some Canadian jurisdictions.

Some key findings in the report:

Effectiveness: Overall, the review found that both stimulants and non-stimulants improved ADHD symptoms in adults. In a few studies, these medications were also found to improve quality of life for adults.

Safety: The review did not identify any safety concerns with these drugs from clinical trials. However, Health Canada has issued several warnings related to these drugs, including the risk of adverse psychiatric and cardiovascular events. As well, there is little clinical data on the long-term safety of stimulants in older adults or people with additional health conditions. The report called for more research into whether side effects of these drugs (i.e. high blood pressure and increased heart rate) may lead to adverse events when used for long durations by older patients.

Misuse: The researchers found low rates of potentially inappropriate prescriptions of these drugs in all provinces. However, their literature review found reports of prescription stimulants being diverted to someone for whom they were not prescribed, especially in college-age adults. They suggest that policies should incorporate strategies to address this risk.

Canadian prescription rates and costs: Between 2009 and 2014, the number of ADHD prescriptions for adults increased by 119 per cent and costs increased by 153 per cent. A total of 5.8 million prescriptions for these drugs were dispensed for adults in the 2013-2014 fiscal year at a cost of $394.1 million.

Variability in use across Canada: The report flagged considerable variation in the rate of ADHD medication use across Canada. The lowest rate of ADHD medication use among adults in 2014 was in Manitoba (38.4 prescriptions dispensed per 1,000 eligible population), with the highest rate of use in Quebec (105.5). Ontario had the third lowest rate (55 prescriptions compared to the national average of 69 per 1,000).

Variability in access across Canada: Most long-acting stimulants are not available or available only with special authorization in many jurisdictions. Additionally, several provinces have placed age restrictions (i.e., coverage up to 18 or 25 years) on long-acting stimulant products, despite a lack of evidence that the drugs lose their efficacy in adulthood.

Challenges in transition from child to adult use: In Ontario, transitioning from a child to adult can lead to a gap in accessing mental health services for patients with ADHD, and this can include breaks in coverage for medication.

“Overall, our report recommends that these medications should be available for adults to treat ADHD, with no evidence to support imposing age restrictions,” said Gomes. “However, we also recommend that more research should be undertaken to better understand the effects of these medications as a person ages, particularly on cardiovascular health. Additionally, health care practitioners should remain vigilant about the potential risks of misuse of these medications.”

About St. Michael's Hospital

St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in 27 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael's Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.

About the Institute for Clinical Evaluative Sciences

The Institute for Clinical Evaluative Sciences (ICES) is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of health care issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health care needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy. For the latest ICES news, follow us on Twitter: @ICESOntario